Ok there's the thing: I had a 2G iPhone and lost it. I didn't want to change my plan so I looked for iPhones on eBay and such. I found one, activated it, got a new SIM card for it, but I ended up not liking the iPhone and returned it. I kept the SIM card though. I was wondering if I could use the SIM card I already have (from the 2G) and put it into a new 3G iPhone without having to change my contract. I'm planing on turning off the 3G network as I'm not really interested in using it if I can keep my old contract.